In-situ compression testing device and system with high rigidity

Abstract

This invention discloses a high-stiffness in-situ compression testing device and system. The testing device includes: a base with a testing area on it; a deformation mechanism mounted on the base; the deformation mechanism includes a deformation part configured to deform towards the testing area when energized, thereby compressing a sample placed in the testing area; a first positioning mechanism mounted on the base; the first positioning mechanism applies a preset pressure away from the testing area to the deformation mechanism; and a second positioning mechanism mounted on the base; the second positioning mechanism positions the sample in the testing area at the end of the deformation mechanism closest to the testing area. This invention can precisely control the deformation displacement of the deformation mechanism, thereby controlling the compressive force exerted by the deformation mechanism on the sample. Simultaneously, due to the high stiffness of the testing device, the elastic energy released by the deformation mechanism is less than the energy required for crack propagation in the tested sample, providing effective experimental data for the reliability assessment of devices made from the tested sample.

Description

Technical Field

[0001] This invention belongs to the field of compression testing technology, and particularly relates to a high-stiffness in-situ compression testing device and system. Background Technology

[0002] When designing any device, fatigue, deformation, fracture, and wear during use should be considered in advance to limit the stress intensity it will bear under actual operating conditions (including axial loads, bending loads, and bearing loads for various conditions). For devices subjected to varying loads, such as aircraft, ships, and vehicles, the design should incorporate non-destructive testing techniques and fatigue theory to provide a testing period for the device. This ensures that any cracks present in the device will not propagate into critical cracks within that period. If the design is flawed, crack propagation instability or even fracture of the material during its service life will cause irreversible damage to the material's performance, with extremely serious consequences.

[0003] The microstructure of materials is a key factor determining their mechanical properties and service reliability. Currently, techniques such as polarizing microscopy, transmission microscopy, and synchrotron radiation can be used to conduct in-situ studies of the microstructural evolution of materials under external loads. In-situ testing devices can investigate the physical and mechanical mechanisms of microstructural deformation and fatigue damage processes under load, thereby optimizing load application schemes to improve the service life of devices made from these materials in practical applications. Crack propagation in materials refers to the dynamic process of crack nucleation and growth under the influence of external factors. Crack propagation has three stages: nucleation, steady-state propagation, and unstable propagation. However, current in-situ compression testing devices struggle to control the steady-state propagation of cracks in the tested samples under external loads, making it impossible to obtain accurate fracture mechanics analysis data and effectively improve the service life of devices made from these materials in practical applications. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of difficulty in controlling the steady-state development of cracks in the tested sample, and this purpose is achieved through the following technical solution:

[0005] A first aspect of the present invention provides a high-stiffness in-situ compression testing device, the high-stiffness in-situ compression testing device comprising:

[0006] A base, on which a test area is provided;

[0007] A deformation mechanism is disposed on the base; the deformation mechanism includes a deformation part, which is configured to deform toward the test area in an energized state to compress the sample placed in the test area;

[0008] A first positioning mechanism is disposed on the base; the first positioning mechanism is used to apply a preset pressure away from the test area to the deformation mechanism;

[0009] A second positioning mechanism is disposed on the base; the second positioning mechanism is used to position the sample in the test area at one end of the deformation mechanism near the test area.

[0010] The high-rigidity in-situ compression testing device of the present invention can precisely control the displacement generated by the elastic deformation of the deformation mechanism, thereby controlling the extrusion force of the deformation mechanism on the sample. At the same time, due to the overall high rigidity of the testing device, the elastic performance released by the deformation mechanism is less than the energy required for crack propagation in the tested sample, so as to control the steady-state development of cracks in the tested sample. Thus, the crack toughening curve of the tested sample is measured, providing effective experimental data for the reliability assessment of the device made from the tested sample. By optimizing the load loading scheme, the service life of the device made from the tested sample can be better improved in practical applications.

[0011] Furthermore, according to the high-stiffness in-situ compression testing apparatus of the present invention, the deformable portion is capable of deformation at least along the length direction of the base and / or along the width direction of the base.

[0012] In some embodiments of the present invention, the deformable portion comprises a piezoelectric material.

[0013] In some embodiments of the present invention, a receiving cavity is provided on the base, and the receiving cavity extends along the length direction of the base;

[0014] A first pressure block is disposed within the accommodating cavity. The deformation mechanism and the test area are disposed within the accommodating cavity and located on opposite sides of the first pressure block. The deformation mechanism has a first side and a second side. The first side is away from the test area, and the second side faces the test area. The end of the accommodating cavity adjacent to the first side is the first end. Along the length direction of the base, the two ends of the deformation mechanism are in contact with the first pressure block and the first end, respectively.

[0015] The first positioning mechanism is connected to the first pressure block. The first positioning mechanism can drive the first pressure block to move toward the deformation mechanism in order to apply a preset pressure to the deformation mechanism.

[0016] In some embodiments of the present invention, the first positioning mechanism includes a plurality of first bolts, which are arranged parallel to each other along the circumference of the first pressure block.

[0017] The plurality of first bolts are respectively connected to the first pressure head and the first end, and the plurality of first bolts are rotatable to drive the first pressure block to move.

[0018] In some embodiments of the present invention, the sum of the stiffness of the plurality of first bolts is 10% to 15% of the stiffness of the deformed portion.

[0019] In some embodiments of the present invention, the high-stiffness in-situ compression testing device further includes a limiting structure along the radial direction of the first bolt, the limiting structure being used to limit the deformation mechanism.

[0020] In some embodiments of the present invention, the limiting structure includes a limiting block, the limiting block being provided with a limiting hole, the size of the limiting hole being adapted to the radial dimension of the deformation mechanism;

[0021] The limiting block is disposed within the accommodating cavity, and the deformation mechanism is limited within the limiting hole;

[0022] The ends of the plurality of first bolts that are furthest from the first pressure block pass through the limiting block and are connected to the first end.

[0023] In some embodiments of the present invention, the high-stiffness in-situ compression testing device further includes:

[0024] A pressure detection mechanism is disposed within the accommodating cavity and located on the side of the test area away from the deformation mechanism; the pressure detection mechanism is used to detect the pressure value of the sample in the test area.

[0025] In some embodiments of the present invention, the high-stiffness in-situ compression testing device further includes a second pressure block, which is located on the side of the first pressure block away from the deformation mechanism; the first pressure block and the second pressure block are disposed opposite to each other, and the test area is located in the area defined by the first pressure block and the second pressure block;

[0026] The pressure detection mechanism is located on the side of the second pressure block away from the test area;

[0027] The second positioning mechanism is located on the side of the pressure detection mechanism away from the second pressure block, and is used to position the pressure detection mechanism and the sample.

[0028] In some embodiments of the present invention, the end of the accommodating cavity adjacent to the second side is the second end, and the second positioning mechanism includes a threaded through hole disposed at the second end and a second bolt that mates with the threaded through hole, wherein the insertion end of the second bolt can abut against the pressure detection mechanism.

[0029] In some embodiments of the present invention, the first pressing block and / or the second pressing block are made of tungsten carbide material.

[0030] A second aspect of the present invention provides an in-situ compression testing system, the in-situ compression testing system comprising a microscope and the high-stiffness in-situ compression testing device proposed in the first aspect of the present invention.

[0031] The test area of ​​the high-stiffness in-situ compression testing device is located within the observation area of ​​the microscope.

[0032] The in-situ compression testing system of the present invention enables dynamic observation and characterization of the microstructural changes of samples under compressive loads under microscope conditions through simple operation. It can be used to study the structural evolution behavior of materials under pressure, analyze the deformation, damage and failure behavior of materials under external loads, optimize load loading schemes, and effectively improve the service life of devices. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 An isometric view of a high-stiffness in-situ compression testing apparatus according to an embodiment of the present invention is shown schematically.

[0035] Figure 2 A cross-sectional view of a high-stiffness in-situ compression testing apparatus according to an embodiment of the present invention is shown schematically.

[0036] Figure 3 A top view of a high-stiffness in-situ compression testing apparatus according to an embodiment of the present invention is shown schematically.

[0037] Figure 4 A schematic diagram of an in-situ compression testing system according to an embodiment of the present invention is shown.

[0038] Figure 5 An exemplary illustration shows the domain evolution process of a perfectly polarized barium titanate single crystal sample under different pressure states, collected by an in-situ compression testing system according to an embodiment of the present invention.

[0039] Figure 6 An exemplary schematic diagram of the clamping of a PZT-5 ceramic sample tested by an in-situ compression testing apparatus according to an embodiment of the present invention is shown.

[0040] Figure 7 An exemplary diagram of steady-state crack propagation in a PZT-5 ceramic sample acquired by an in-situ compression testing system according to an embodiment of the present invention is shown.

[0041] Figure 8 An exemplary fracture toughening curve is shown, obtained from crack data of a PZT-5 ceramic sample acquired by an in-situ compression testing system according to an embodiment of the present invention.

[0042] The attached figures are labeled as follows:

[0043] 100. High-rigidity in-situ compression testing device; 200. Microscope; 10. Base; 11. Receptacle; 12. Wire hole; 13. Wire groove; 14. Threaded through hole; 15. First end; 16. Second end; 20. Deformation mechanism; 21. Signal line of the deformation part; 30. Test area; 31. Three-point bending fixture; 40. First positioning mechanism; 51. First pressure block; 52. Second pressure block; 60. Pressure detection mechanism; 61. Pressure sensor; 62. Fixing ring; 63. Signal line of pressure sensor; 70. Limiting structure; 71. Limiting block; 72. Limiting hole; 80. Second positioning mechanism; 81. Second bolt; 90. Sample. Detailed Implementation

[0044] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0045] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0046] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0047] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0048] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and examples can be combined with each other.

[0049] like Figures 1-3 As shown, according to an embodiment of the present invention, a high-stiffness in-situ compression testing device 100 is proposed. The high-stiffness in-situ compression testing device 100 is used to test the compressive performance parameters of a material under compressive load, reflecting the evolution of its microstructure. The high-stiffness in-situ compression testing device 100 includes a base 10. The structure of the base 10 is not limited and can be designed according to requirements; for example, the base 10 may be a frame structure. The material of the base 10 is also not limited and can be selected according to requirements; for example, the base 10 may be made of stainless steel, providing rigid support for other components mounted on the base 10, while also being corrosion-resistant. A test area 30 is provided on the base 10, for placing the sample 90 to be tested. The sample 90 can be a ductile or brittle material.

[0050] The high-stiffness in-situ compression testing device 100 also includes a deformation mechanism 20, which is disposed on the base 10. The deformation mechanism 20 can compress the sample 90 placed in the test area 30. The deformation mechanism 20 includes a deformation section, which is configured to deform toward the test area 30 in the energized state to compress the sample 90 placed in the test area 30. The base 10 cooperates with the deformation mechanism 20 to apply pressure to the sample 90 and provides protection for the deformation mechanism 20 and the test area 30 of the sample 90. The material of the deformation section in this embodiment has the property of deforming under applied voltage. The deformation section includes, for example, a piezoelectric material or a dielectric elastomer. The piezoelectric material can be one of inorganic piezoelectric materials (such as piezoelectric crystals or piezoelectric ceramics), organic piezoelectric materials (such as polyvinylidene fluoride), or composite piezoelectric materials. The dielectric elastomer can be one of polyacrylate elastomers, silicone resins and their composites, or polyurethanes and their composites. The base 10 has a wire hole 12 for the signal line 21 of the deformation part to extend out. The signal line 21 of the deformation part is connected in sequence to a high voltage power supply (not shown in the figure) and a signal generator (not shown in the figure).

[0051] The arrangement of the deformable part is not limited; in some embodiments, such as... Figures 1-3 As shown, the deformation mechanism 20 is entirely composed of a deformation section. When energized, the entire deformation mechanism 20 deforms towards the test area 30. In other embodiments (not shown in this example figure), a portion of the deformation mechanism 20 is composed of the deformation section. The deformation mechanism 20 includes a body that extends along the length of the base 10 (refer to...). Figure 2 Extending in the direction shown by the X-axis, the body has at least one deformable part. When energized, only the deformable part deforms towards the test area 30. In one example, the deformable part is located at the end of the body closer to the test area 30; in another example, the deformable part is located at the end of the body farther from the test area 30; in yet another example, the deformable part is distributed along the length and / or width direction of the body. The number of deformable parts can be one or more, and they can be arranged in various forms on the body to achieve different compression effects on the sample 90 within the test area 30.

[0052] The high-stiffness in-situ compression testing device 100 also includes a first positioning mechanism 40, which is mounted on the base 10. The first positioning mechanism 40 is used to apply a preset pressure away from the test area 30 to the deformation mechanism 20. By applying the preset pressure to the deformation mechanism 20, the deformation mechanism 20 can be positioned, and its mechanical properties can be improved. The deformation displacement of the deformation mechanism 20 can be better controlled, thereby controlling the compressive force of the deformation mechanism 20 on the sample 90 and controlling the steady-state development of cracks in the sample 90. This not only improves the accuracy of fracture analysis data for ductile materials but also provides more accurate analysis data for the fracture process of brittle materials, solving the problem of inaccurate test results for crack data of brittle materials. It can realize the dynamic observation of the microstructural changes of brittle materials under compression and bending loads under the microscope 200, the dynamic observation of the steady-state crack propagation of brittle materials, and the acquisition of crack toughening curves of brittle materials, providing effective experimental data for the reliability assessment of devices made of brittle materials.

[0053] The high-stiffness in-situ compression testing device 100 also includes a second positioning mechanism 80, which is disposed on the base 10. The second positioning mechanism 80 is used to position the sample 90 in the test area 30 at one end of the deformation mechanism 20 near the test area 30, so as to avoid the sample 90 shifting when the deformation mechanism 20 applies extrusion force to the sample 90, thereby reducing the accuracy of the fracture mechanics data.

[0054] According to the high-rigidity in-situ compression testing device 100 of the present invention, the compressive force of the deformation part on the sample 90 in the test area 30 is controlled by setting a deformation part and controlling the energizing voltage of the deformation part. Simultaneously, due to the overall structural design of the testing device, the device as a whole possesses high rigidity characteristics, ensuring that the elastic performance released by the deformation mechanism 20 is less than the energy required for crack propagation in the tested sample 90, thereby controlling the steady-state development of cracks in the tested sample 90. This allows for the measurement of the crack toughening curve of the tested sample 90, providing effective experimental data for the reliability assessment of devices made from the tested sample 90. Furthermore, by optimizing the load loading scheme, the service life of devices made from the tested sample 90 in practical applications can be further improved.

[0055] In some embodiments of the present invention, such as Figures 1-3 As shown, the deformable portion is capable of deformation at least along the length direction of the base 10 and / or along the width direction of the base 10. In one example, such as Figures 1-3 As shown, the deformable part extends along the length direction of the base 10 (refer to...). Figure 2(As shown by the X-axis in the figure), the test area 30 is located at one end of the length direction of the base 10. When energized, the deformable part deforms along the length direction of the base 10 to perform high-precision compression of the sample 90 within the test area 30. In another example (not shown in the example figure), the deformable part deforms along the width direction of the base 10 (refer to the width direction of the base 10). Figure 2 Extending in the direction shown by the Y-axis, the test area 30 is located at one end of the width direction of the base 10. In the energized state, the deformation part deforms along the width direction of the base 10 to uniformly compress the sample 90 within the test area 30. Of course, in this embodiment, the deformation part can also deform simultaneously along the length direction and the width direction of the base 10 in the energized state. The test area 30 can be located at one end of the length direction or one end of the width direction of the base 10.

[0056] In some embodiments of the present invention, a receiving cavity 11 is provided on the base 10, extending along the length direction of the base 10. The first receiving cavity 11 is used to protect the components disposed therein. A first pressure block 51 is disposed within the receiving cavity 11. A deformation mechanism 20 and a test area 30 are disposed within the receiving cavity 11 and located on opposite sides of the first pressure block 51. The deformation mechanism 20 has a first side and a second side. The first side is away from the test area 30, and the second side faces the test area 30. The end of the receiving cavity 11 adjacent to the first side is a first end 15. Along the length direction of the base 10, the two ends of the deformation mechanism 20 are in contact with the first pressure block 51 and the first end 15, respectively. The compressive force generated by the deformation of the deformation part of the deformation mechanism 20 can be uniformly applied to the sample 90 located in the test area 30 through the first pressure block 51.

[0057] The first positioning mechanism 40 is connected to the first pressing block 51. The first positioning mechanism 40 can drive the first pressing block 51 to move towards the deformation mechanism 20 to apply a preset pressure to the deformation mechanism 20, ensuring that the deformation mechanism 20 does not work under no-load conditions, thereby obtaining better mechanical properties of the sample 90. The magnitude of the preset pressure can be adjusted as needed. One way the first positioning mechanism 40 applies the preset pressure to the deformation mechanism 20 is by pushing the first pressing block 51 towards the deformation mechanism 20. For example (not shown in the example figure), a push rod can be provided on the side of the first pressing block 51 near the test area 30, and the push rod pushes the first pressing block 51 towards the deformation mechanism 20. Another way the first positioning mechanism 40 applies the preset pressure to the deformation mechanism 20 is by pulling the first pressing block 51 towards the deformation mechanism 20. For example, as shown in the example figure... Figures 1-3As shown, the first positioning mechanism 40 includes multiple first bolts, which are arranged parallel to each other along the circumference of the first pressure block 51. The multiple first bolts are respectively connected to the first pressure block 51 and the first end 15, and are rotatable to drive the first pressure block 51 to move. For example, when the multiple first bolts are turned in the forward direction, they move towards the deformation mechanism 20, thereby driving the first pressure block 51 to move towards the deformation mechanism 20; when the multiple first bolts are turned in the reverse direction, they move away from the deformation mechanism 20, thereby driving the first pressure block 51 to move away from the deformation mechanism 20.

[0058] When the first bolt is tightened, causing the first pressure block 51 to apply a preset pressure to the deformation mechanism 20, the deformation part will deform under energized conditions. This deformation will cause the first bolt to stretch. The stretching of the first bolt will transfer the compressive force (compressive load) from the compression deformation part onto the sample 90 in the test area 30 through the first pressure block 51, thus compressing the sample 90. The first bolt is made of a material with a certain elastic deformation, such as stainless steel. The first pressure block 51 is made of a material with high rigidity. During the test, the deformation of the first pressure block 51 is small, which ensures that the compressive load generated by the deformation of the deformation part 20 is uniformly applied to the sample 90 without affecting the output accuracy of the deformation displacement of the deformation part. At the same time, the low elasticity of the first pressure block 51 is beneficial to the control of the steady-state crack propagation of the sample 90. The material of the first pressure block 51 is, for example, tungsten carbide. In a preferred embodiment, the sum of the stiffness of the plurality of first bolts is 10% to 15% of the stiffness of the deformed part, preferably 15%. Within this range, it is beneficial for the displacement output of the deformation mechanism 20, so that the deformation mechanism 20 generates a compressive force on the sample 90. When the sum of the stiffness of the plurality of first bolts is greater than 15% of the stiffness of the deformed part, the deformation of the plurality of first bolts cannot accurately output the displacement of the deformed part. When the sum of the stiffness of the plurality of first bolts is less than 10% of the stiffness of the deformed part, the deformed part cannot be effectively fixed.

[0059] In some embodiments of the present invention, such as Figures 1-3 As shown, the high-stiffness in-situ compression testing device 100 also includes a limiting structure 70. Along the radial direction of the first bolt, the limiting structure 70 is used to limit the deformation mechanism 20, preventing eccentric loads from being generated when the first positioning mechanism 40 applies a preset pressure to the deformation mechanism 20. In one example (not shown in the example figure), the limiting structure 70 includes multiple limiting bosses distributed on both sides of the width direction of the accommodating cavity 11. A limiting groove is provided at the position corresponding to the limiting boss on the deformation mechanism 20, and the limiting boss and the limiting groove cooperate. In another example, such as... Figures 1-3As shown, the limiting structure 70 includes a limiting block 71 with a limiting hole 72. The size of the limiting hole 72 is adapted to the radial dimension of the deformation mechanism 20. The limiting structure 70 is disposed within the receiving cavity 11, and the deformation mechanism 20 is limited within the limiting hole 72. The ends of the multiple first bolts furthest from the first pressure block 51 pass through the limiting block 71 and are connected to the first end 15. In this embodiment, the deformation mechanism 20 is radially limited by the limiting block 71, resulting in a simpler structure and process.

[0060] In some embodiments of the present invention, such as Figures 1-3 As shown, the high-stiffness in-situ compression testing device 100 also includes a pressure detection mechanism 60, which is disposed within the accommodating cavity 11 and located on the side of the test area 30 away from the deformation mechanism 20. The pressure detection mechanism 60 is used to detect the pressure value experienced by the sample 90 within the test area 30, and to analyze the microscopic changes in the crack data of the sample 90 based on the detected pressure value during the compression test.

[0061] In some embodiments of the present invention, the high-stiffness in-situ compression testing device 100 further includes a second pressure block 52, which is located on the side of the first pressure block 51 away from the deformation mechanism 20. The first pressure block 51 and the second pressure block 52 are arranged opposite to each other, and the test area 30 is located in the area defined by the first pressure block 51 and the second pressure block 52. This solves the problem of the test area 30 having high limitation on the size of the sample 90, and provides a wider range of sample 90 sizes. The material of the second pressure head is the same as that of the first pressure head, for example, both are made of tungsten carbide. Tungsten carbide has the characteristic of high stiffness, and the deformation of the first pressure block 51 and the second pressure block 52 made of tungsten carbide can be ignored. This allows the force exerted on the sample 90 by the deformation mechanism 20 and the second positioning mechanism 80 to be uniformly applied to the sample 90, achieving uniform control of the compressive force on the sample 90 and controlling the steady-state development of cracks in the sample 90.

[0062] The pressure detection mechanism 60 is located on the side of the second pressure block 52 away from the detection area of ​​the sample 90. The compressive force on the sample 90 is evenly transmitted to the pressure detection mechanism 60 through the second pressure block 52, thereby obtaining more accurate pressure detection data. In some embodiments, the pressure detection mechanism 60 includes a sensor fixing ring 62 and a pressure sensor 61 located within the sensor fixing ring 62. The pressure sensor 61 detects the pressure data received by the sample 90. The sensor fixing ring 62 is used to fix the pressure sensor 61 and to avoid eccentric pressure during pressure measurement, which would lead to inaccurate measurement results. A wire groove 13 is also provided at the position corresponding to the pressure sensor 61 on the base 10 to allow the signal line 63 of the pressure sensor to extend. The signal line 63 of the pressure sensor is connected to a data acquisition card (not shown in the figure), which is used to collect the pressure data detected by the pressure sensor 61.

[0063] In some embodiments of the present invention, such as Figures 1-3 As shown, the end of the accommodating cavity 11 adjacent to the second side is the second end 16. In one example (not shown in the example figure), the second positioning mechanism 80 includes a stop block disposed between the pressure detection mechanism 60 and the second end 16. The pressure of the pressure detection mechanism 60 is adjusted by adjusting the number of stops. When the maximum pressure of the pressure detection mechanism 60 reaches a preset value, the sample 90 and the pressure detection mechanism 60 are positioned simultaneously. In another example, as shown... Figures 1-3 As shown, the second positioning mechanism 80 includes a threaded through hole 14 at the second end 16 and a second bolt 81 that mates with the threaded through hole 14. The insertion end of the second bolt 81 can abut against the pressure detection mechanism 60. Tightening the second bolt 81 can initially fix the sample 90 between the first pressure block 51 and the second pressure block 52, and provides adjustment space for samples 90 of different sizes. Continuing to tighten the second bolt 81 will make the pressure value of the pressure detection mechanism 60 reach the preset value, thereby simultaneously fixing the sample 90 and the pressure detection device, preventing the pressure detection mechanism 60 from slipping and causing inaccurate measurement results. In addition, the first pressure block 51 and the second pressure block 52, together with the deformation mechanism 20 and the second bolt 81, apply pressure to the sample 90, so that the force applied by the deformation mechanism 20 and the second bolt 81 to the sample 90 is evenly loaded onto the sample 90 through the first pressure block 51 and the second pressure block 52.

[0064] According to an embodiment of the present invention, an in-situ compression testing system is proposed, such as... Figure 4 As shown, the in-situ compression testing system includes a microscope 200 and a high-stiffness in-situ compression testing device 100 disclosed in the above embodiments and examples. The testing area 30 of the high-stiffness in-situ compression testing device 100 is located within the observation area of ​​the microscope 200.

[0065] The in-situ compression testing system of this embodiment enables dynamic observation and characterization of the microstructural changes of sample 90 under compressive load under microscope 200 through simple operation. It can be used to study the structural evolution behavior of microstructure of ductile and brittle materials under pressure, analyze the deformation, damage and failure behavior of materials under external load, optimize load loading schemes, and effectively improve the service life of devices.

[0066] The following is a detailed description of how to use the compression testing system in this embodiment:

[0067] First, place the compression testing device on the operating stage of the microscope 200. Then, place the sample 90 within the testing area 30 and adjust the testing area 30 to be within the observation area of ​​the microscope 200. Activate the deformation mechanism 20. The signal generator sends a power supply signal to the high-voltage power supply, which provides voltage to the deformation mechanism 20. The deformation part deforms, applying pressure to the sample 90. Use a data acquisition card to collect the pressure data detected by the pressure detection mechanism 60. Use the high-speed camera built into the microscope 200 to observe and record the microstructural changes of the sample 90.

[0068] Taking the in-situ observation of the domain evolution process of a perfectly polarized barium titanate single crystal sample 90 under different pressure states as an example, a perfectly polarized barium titanate single crystal sample 90 with dimensions of 2mm*2mm*0.3mm was placed in the test area 30 of a high-stiffness in-situ compression testing device 100, and referenced... Figure 5 Crack propagation diagram of sample 90, sample 90 along Figure 5 The cutting direction indicated by the arrow at point P is along the direction of the applied force. Figure 5 The direction indicated by the arrow at point P is that the polarization direction is parallel to the force loading direction. Adjust the first positioning mechanism 40 to apply a preset pressure to the deformation mechanism 20, and slowly adjust the second bolt 81 to fix the sample 90 until the pressure value detected by the pressure detection mechanism 60 reaches the preset value. Then, by energizing the deformation part, pressure is applied to the sample 90 through the deformation of the deformation part. The force-induced domain change behavior of the sample 90 is observed using a microscope 200 and recorded using a high-speed camera. Figure 5 This describes the domain evolution of a perfectly polarized barium titanate single crystal sample 90 under different pressure conditions. Figure 5 As shown, I is the crack state diagram of sample 90 in its initial state; II is the crack state diagram of sample 90 under a pressure of 6 MPa; III is the crack state diagram of sample 90 under a pressure of 6.5 MPa; IV is the crack state diagram of sample 90 under a pressure of 13 MPa; V is the crack state diagram of sample 90 under a pressure of 5 MPa; and VI is the crack state diagram of sample 90 under a pressure of 0 MPa. Figure 5 It can be seen that the pressure exerted on the perfectly polarized barium titanate single crystal sample 90 extends steadily under the range of 0-13 MPa. The service life of devices made from perfectly polarized barium titanate single crystal materials can be improved by optimizing the load loading scheme.

[0069] Taking the in-situ observation of the crack change process of PZT-5 ceramic sample 90 under different forces as an example, a three-point bending fixture 31 is installed in the test area 30 between the first pressure block 51 and the second pressure block 52 (the three-point bending fixture 31 is not mandatory and can be selected for use depending on the shape of the sample 90 being tested), and the PZT-5 sample 90 with a pre-made V-shaped notch is placed in the test area 30. The effect after placement is as follows. Figure 6As shown. During placement, ensure the pre-made V-shaped notch is aligned with the middle roller of the three-point bending fixture 31. Adjust the first positioning mechanism 40 to apply a preset pressure to the deformation mechanism 20, and slowly adjust the second bolt 81 to fix the sample 90, while simultaneously applying a preload to the sample 90. Then, by energizing the deformation part, the deformation part slowly applies displacement to the sample 90 to apply an external load, while observing the crack propagation process of the sample 90 through the high-speed camera configured in the microscope 200. Due to the reaction force generated by the deformation of the sample 90, stress concentration occurs at the tip of the V-shaped notch, and cracks appear in the V-shaped notch as the displacement increases. At this time, record the loading displacement, loading force, and crack photographs using a data acquisition device, measure the crack length based on the photographs, and calculate the crack toughening curve of the PZT-5 ceramic using the following formula:

[0070]

[0071] Where P is the external load on sample 90, L is the span of the three-point bending fixture 31, B is the thickness of sample 90, W is the height of sample 90, and a is the distance from the crack tip to the notch edge. The geometry factor of sample 90 is given by the following formula:

[0072]

[0073] The steady-state crack propagation process of the PZT-5 ceramic sample 90 in this embodiment is shown in the attached figure. Figure 7 As shown, 7a represents the crack state diagram when the external load is 39.14 N, 7b represents the crack state diagram when the external load is 44.45 N, 7c represents the crack state diagram when the external load is 49.04 N, 7d represents the crack state diagram when the external load is 51.07 N, 7e represents the crack state diagram when the external load is 54.41 N, and 7f represents the crack state diagram when the external load is 57.88 N. The fracture toughening curve calculated according to the above formula is shown below. Figure 8 As shown. Due to the overall structural design of the testing device in this embodiment, the testing device has high rigidity. During the loading process of the deformation mechanism 20, the deformation energy stored in the testing device is less than the energy required for crack propagation. Therefore, steady-state crack propagation can be achieved, thereby enabling the measurement of the crack toughening curve of brittle materials.

[0074] Of course, the in-situ compression testing system of this embodiment can perform operations not only on the domain evolution process of sample 90 under different pressure states shown in the case, but also on other microstructure evolution behaviors such as fatigue, creep, and fracture of materials under different pressure states.

[0075] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high stiffness in-situ compression testing device, characterized by, The high-stiffness in-situ compression testing device includes: A base, on which a test area is provided; A deformation mechanism is disposed on the base; the deformation mechanism includes a deformation part, which is configured to deform toward the test area in an energized state to compress the sample placed in the test area; A first positioning mechanism is disposed on the base; the first positioning mechanism is used to apply a preset pressure away from the test area to the deformation mechanism; A second positioning mechanism is disposed on the base; the second positioning mechanism is used to position the sample in the test area at one end of the deformation mechanism near the test area; The base is provided with a receiving cavity, which extends along the length direction of the base; A first pressure block is disposed within the accommodating cavity. The deformation mechanism and the test area are disposed within the accommodating cavity and located on opposite sides of the first pressure block. The deformation mechanism has a first side and a second side. The first side is away from the test area, and the second side faces the test area. The end of the accommodating cavity adjacent to the first side is the first end. Along the length direction of the base, the two ends of the deformation mechanism are in contact with the first pressure block and the first end, respectively. The first positioning mechanism is connected to the first pressure block, and the first positioning mechanism can drive the first pressure block to move toward the deformation mechanism so as to apply a preset pressure to the deformation mechanism; The first positioning mechanism includes a plurality of first bolts, which are arranged in parallel intervals along the circumference of the first pressure block; The plurality of first bolts are respectively connected to the first pressure head and the first end, and the plurality of first bolts are rotatable to drive the first pressure block to move; The sum of the stiffness of the plurality of first bolts is 10% to 15% of the stiffness of the deformed part.

2. The high-stiffness in-situ compression testing device according to claim 1, characterized in that, The deformable portion is capable of deformation at least along the length direction of the base and / or along the width direction of the base.

3. The high-stiffness in-situ compression testing device according to claim 1, characterized in that, The deformable part includes a piezoelectric material.

4. The high-stiffness in-situ compression testing device according to claim 1, characterized in that, The high-rigidity in-situ compression testing device also includes a limiting structure, which is used to limit the deformation mechanism along the radial direction of the first bolt.

5. The high-stiffness in-situ compression testing device according to claim 4, characterized in that, The limiting structure includes a limiting block, and a limiting hole is provided on the limiting block. The size of the limiting hole is adapted to the radial dimension of the deformation mechanism. The limiting block is disposed within the accommodating cavity, and the deformation mechanism is limited within the limiting hole; The ends of the plurality of first bolts that are furthest from the first pressure block pass through the limiting block and are connected to the first end.

6. The high-stiffness in-situ compression testing device according to claim 1, characterized in that, The high-stiffness in-situ compression testing device also includes: A pressure detection mechanism is disposed within the accommodating cavity and located on the side of the test area away from the deformation mechanism; the pressure detection mechanism is used to detect the pressure value of the sample in the test area.

7. The high-stiffness in-situ compression testing device according to claim 6, characterized in that, The high-stiffness in-situ compression testing device further includes a second pressure block, which is located on the side of the first pressure block away from the deformation mechanism; the first pressure block and the second pressure block are arranged opposite to each other, and the test area is located in the area defined by the first pressure block and the second pressure block; The pressure detection mechanism is located on the side of the second pressure block away from the test area; The second positioning mechanism is located on the side of the pressure detection mechanism away from the second pressure block, and is used to position the pressure detection mechanism and the sample.

8. The high-stiffness in-situ compression testing device according to claim 7, characterized in that, The end of the accommodating cavity adjacent to the second side is the second end. The second positioning mechanism includes a threaded through hole provided at the second end and a second bolt that mates with the threaded through hole. The insertion end of the second bolt can abut against the pressure detection mechanism.

9. The high-stiffness in-situ compression testing device according to claim 8, characterized in that, The first and / or the second compact are made of tungsten carbide material.

10. An in-situ compression testing system, characterized in that, The in-situ compression testing system includes a microscope and the high-stiffness in-situ compression testing device as described in any one of claims 1-9; The test area of ​​the high-stiffness in-situ compression testing device is located within the observation area of ​​the microscope.

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